Axial type hydrodynamic machine



A. GR AD AXIAL TYPE HYDRODYNAMIC MACHINE Dec. 4, 1951 6 Sheets-Sheet 1 Filed May 5, 1947 INVENTOR. ADOLF G RAD ATTORNEY Dec. 4, 1951 A. GRAD 2,577,242

AXIAL TYPE HYDRODYNAMIC MACHINE Filed May 5, 1947 6 Sheets-Sheet 3 INVENTOR. A D O L F G R A D BY A TTORNE Y i i 2 5E AooLF R BY 7 I ATTORNEY A. GRAD AXIAL TYPE HYDRODYNAMIC MACHINE 6 Sheets-Sheet 5 Dec. 4, 1951 Filed May 5, 1947 g kg INVENTOR. ADOLF GRAD ATTORNEY FIG. IO 93 v 67 Dec. 4, 1951 A. GRAD 2,577,242

AXIAL TYPE HYDRODYNAMIC MACHINE Filed May 5, 1947 6 Sheets-Sheet 6 "5 INVENTOR.

"He ADOLF GRAD l I20 9 I BY WM TTORNEY Patented Dec. 4, 1 951 AXIALTYPEHYDRODYNAM'IC MACHINE Adolf? Grad; Wauwatosa, Wis, assignor to The Oilgear Company Milwaukee,-, Wis-.,. acorpora tion of. Wisconsin:

ApplicationMay 1947; Serial No: 746,018

26 Glaims; 13

ThiSiilVGIlfibh relates to rotary: hydrodynamic Another obj ect to" provide an axial type hydrodynamic machine which when functioning as a pump is=capab1e of delivering a largevolume of liquid at a; very high pressure.

A'nother ohj e'ct is to improve the construction" of axial type hydrodynamic"machinesa Other objects and advantages will be apparent from theidescription hereinafter givenof a hydrodynamic maehir'ie in which the invention is embodied;

Since the functions-era pump-and" thezfunc' tions of a motor are suhst'antially oppositeito each other, a machineembodying:the' invention will be referred to herein as a piump but the invention is equally" app'li'cabl'to' a motor and it is to beunderstood that" the term pump as used herein means a: hydrodynamic machine regardless of Whether" the ma'chines functions asa" pump or: as a motor:

The invention is exemplified by the pump shown? in" the i accompanying: drawings 1 in: which the views: are as follows Fig; 1 is a longitudinal'horizon'tal section takenthrough-: the center'of' thapump and showing the parts in the positions occupiediwhenipum displacement is": substantially zerogthef plane of the'vi'ew'being'indicated by the line II ofFig. 3.

Fig: 2 1s a---longitudinalvertical'lsection through the pump .1 showing" the parts in the positions occupied when pump" displacement is substantiallYmaxiinum; the plane of the view being indicated by the irregular line 2'--2- of Fig. 3.

Fig; 3 isan end view of 'thepumpwith' apart- 'of th'e:- gear. pump housing 'shown in sectionin order to" expose certain channels; the view beingt'ak'en on" the lines-3 ofFig. 2" and drawn to a scale largerthan that-ofFigs;'l and 22 Figz-t is a face view-ofthe-valve whichcontrols 2 the new of liquid to and fromthe' pump eynnders, the plane of the view being indicated bytheline 4 -4 of Figi2:

Fig." 5 'isa' section through the valve and portions of the adjacent parts, the plane of the view-'being indicated by the line 5 -5 of Fig; 4'.

Fig6 is avert'ical section taken on the line E6 ofFig; 2;

Fig. T is a vertical transverse section taken on the=line Tl of Fig. 2 and showing thearrangement of the pistons and'cylinders in the cylinder barrel;

FigZBisa transversevertic'al section taken on the: irregular line 8+8 of r Fig. 1 and showing means for 'ad'justing pump displacement and certain detailsof 'a valve like element which functionsas a thrust" bearing.

Fig. 9 is a face view of the valve like element shownin Figs. I, 2 and 8; the view being taken in' the plane indicated bythe'line 9 9 of Fig. 2 an'd 'drawn to-a' larger scale; Fig; 10' is a section through the valve like element and portions-ofad'jacent parts, the view heing' drawn t6 the same scale as Fig. 9 and taken in'the planeindicat'ed by the line Iii-40 0f that figure:

Fig; 11 is a circuit diagram illustrating' the manner-"inwhich liquid is supplied to the holdup motors-shown in Figs. 8'-10,' the upper part of the diagram being a partial section taken on the=line* A--A of Fig; 9 and drawn to a larger scale.

Fig; 12 is a diagram of-- a hydraulic circuit which effects retraction ofthe pump pistons;

The pump chosen for illustration has its mechanismarrangedwithin and supported'by a housingor case I' which has a removable end head 2 at' it's' rear'end and is provided'with suitable supporting" brackets notshown. v

Case I" encloses a rotatable cylinder barrel 3 which is fi'xed to a drive shaft 4 and is rotatably supportedat its rear end hy'a bearing carried by endh'ead" 2E Sl'i'aift 4 is supported near its front end by a hearing 6' carried by the front walfo'fcase' l so that 'cylinder barrel 3'is supported for rotation upon an axiswhich is horiz'ontalin respect to Fig. 2.

Cylinder barrel 3 has *a-plurality of cylinders T'8 and pistons .l- -l'll arranged therein around andparall'el to its axis of'rotat'ion. Each cylinder includes" an outer or [forward portion 1 whichv extends inward'fr'om thefront' end of cylindenbarrel 3, and a'coax'ial inner orj rear portion 8 which" is smaller than portion 1' and extendsrearward' 'therefrom; Each piston in cludes a non-pumping portion 9, which is of substantially the same diameter as the cylinder portion I and is closely fitted for reciprocation therein, and a coaxial pumping portion II! which is of substantially the same diameter as cylinder portion 8 and is closely fitted for reciprocation therein. Portions 9 and Ill are fixed to or formed integral with each other and provide a shoulder II at the junction of the two portions.

Each piston 9!9 is forced inward mechanically and the pumping portion I9 thereof ejects liquid from the inner portion 8 of its cylinder during one-half of each revolution of cylinder barrel 3 and. each piston 9-49 is retracted or moved outward and draws liquid into the portion 8 of its cylinder during the other half of each revolution of cylinder barrel 3 a will presently be explained.

Retraction of pistons 9--I9 may be accomplished in any suitable manner but preferably they areretracted by fluid pressure such as by liquid which is supplied at a low pressure to the rear ends of cylinder portions I and acts upon shoulders I I. Liquid under pressure may be supplied to the rear ends of cylinder portions I in any suitable manner from any suitable source.

As shown, shaft 4 has the rear portion thereof reduced in diameter and extended through end head 2 to drive a gear pump from which liquid is supplied to cylinder portions i through a passage I5 which extends axially through the reduced rear portion of shaft 4, a passage I 6 which extends radially from passa e I5 and opens into an annular groove II formed in the peripheral surface of shaft 4, and a plurality of passages I8 one of which extends from each cylinder portion I through the wall of cylinder barrel 3 into communication with groove IT.

The gear pump (Figs. 13) has its driven gear I9 fixed upon the rear end portion of shaft 4 and its idler gear 29 rotatably supported by a stub shaft 2I which is carried by a gear pump housing 22 fixed to the rear end of end head 2. Gears I9 and 29 are arranged within a suitable recess 23 which is formed in housing 22 and is divided by gears I9 and 29 into an intake chamber 24 and a discharge chamber 25. Recess 23 ha its open side closed by a plate 25 which is clamped between housing 22 and the rear face of end head 2.

Intake chamber 24 is connected by a channel 21 t a source of liquid supply such as a reservoir 28 as'shown schematically in Fig. 12. Discharge chamber 25 opens into a passage 29 which is formed in housing 22 and communicates with an annular groove 39 formed in the rear end portion of shaft 4. Opposite sides of groove 30 are connected by a passage 3! which extends through shaft 4 and communicates with passage I5 so that liquid from gear pump I929 may flowfrom discharge chamber 25 through passage 29, groove 30, passages 3!, I5 and I6, groove I! and passages I8 t the inner ends of cylinder portions 1,

For the purpose of illustration, the pump has been shown provided with manually operated means for varying its displacement as will presently be explained but in practice it preferably is provided with hydraulically operated displacement varying means. In order that the liquid discharged by gear pump I92!l may be employed for operating the displacement varying means and/or for other purposes, passage 29 has been shown as having connected thereto a channel 32 through which liquid may be directed from gear pump I920 to a remote point or points. The

4 liquid discharged by gear pump I9-20 in excess of requirements is exhausted through a relief valve 33 (Fig. 12) which discharges through a channel 34 into reservoir 28 and which enables gear pump Ill-29 to maintain a predetermined low pressure in the several passages and channels and in the cylinder portions I.

Each piston 9--I D is moved inward during onehalf of each revolution of cylinder barrel 3 by means to be presently described and each piston is moved outward during the other half of each revolution of cylinder barrel 3 by the pressure in cylinder portion 1 acting upon shoulder II. The inward moving pistons eject liquid from the cylinder portions 1 in which they are fitted and this liquid flows through passages I8 and groove IT to the cylinder portions I containing the outward moving pistons. Since the sum of the displacements of the inward moving pistons is the same as the sum of the displacements of the outward moving pistons, gear pump I920 need supply to cylinder portions I only suflicient liquid to make up for leakage losses.

The inward moving pistons eject liquid from the portions 8 of the cylinders in which they are fitted and the outward moving pistons draw liquid into the portions 8 of the cylinders in which they are fitted. Liquid flows to and from each cylinder portion 8 through a passage 49 extending therefrom inward and rearward through the rear face of cylinder barrel 3 which is made flat and smooth and constitutes a valve seat 4| for afloating fiat valve 42 which controls the flow of liquid to and from cylinder portions 8. Valve seat 4| has been shown as being formed upon a hardened insert 3a which has portions of passages 40 formed therein and which is rigidl secured in cylinderbarrel 3 to form substantially an integral part thereof but cylinder barrel 3 may be made of a single piece of material if desired.

Valve seat 4I engages an annular valve face 43 (Figs. 4 and 5) which protrudes slightly from the front end of valve 42 and is made flat and smooth. Valve 42 is supported by two pins 44 (Figs. 1 and 4) which are inserted into it and. into end head 2. Pins 44 revent valve 42 from rotating but they have sufficient clearance to permit valve 42 to be so adjusted that its face 43 bears evenly upon valve seat 4 I During rotation of cylinder barrel 3, each passage 40 registers alternately with two crescent shaped valve ports 45 and 46 which extend into valve 42 from its face 43, the adjacent ends of ports 45 and 45 being spaced apart a distance equal to or slightly greater than the width of a passage 40 in order to provide a seal between the two ports.

Ports 45 and 45 are connected through a plurality of hold-up motors to two passages 41 and 48 which are formed in end head 2 and are adapted to be connected to opposite sides of an external circuit as by means of two channels 49 and'5il. As shown, two holes 5I extend rearward from the bottom of port 45 into communication with two hold-up motors 52 which are arranged within valve 42 and communicate with passage 4? through two passages 53 formed in end head 2, and two holes 54 extend rearward from the bot tom of port 46 into communication with two hold-up motors 55 which are arranged within valve 42 and communicate with passage 48 through two passages 5'5 formed in end head 2.

All four of the hold-up motors 52 and 55 are identical and each includes a cylinder 51 which is formed in valve 42 concentric with a hole 5I armamon-S-A; arhollow pistomi8:whicheisrcloseliiifitterbirrz eylindercifhto; slider thereim-gane azmulamfsealingr memberrSll-awhichzis. arrangedrbetweempistomfifir and :the:-rear:face:oi .end'rheadiz, :andi arsm'ing fifia which i'searra-ngedmithirrrcylinderrfiis. (By-linden;- 51,-;hollow ipistions53and;annulansealinggmember Elk-thus.formiaurchannelrforzthevfreerflowrof liquidq hetweerrrazholeqfilwr Mranclea passage-'53: orsieiu 'Ihe:--a=buttmgsurfaces; of: sealing; member-i 59: endendEhead-Z are made-flat andfsmooth andrthee abutting isurfac'esofi sealing; member; 59m n at pi" ton-1 58' are: made spherical. and smooth 1 to form 1 substantially liquid tight joints between valveslw and end; head;- 2; and: to r permit. valve; 62: to: so adjust: itself thatvaile, t: the:- sealing-: members. bear:evenly-,-upon the reanfaeeeofzenelrheadiz fandi therfacee 43:;=O.'va1Yef.4-2- bears; uniformly; upon valve seatJH Spring :Gbmrgesmistem 58 against. sealing, member" 59, and. sealing member; 59\ against end ahead-2; -,ancltthe (springs 6!) oi all of therholdeup -m0.tors:-urge :va1ve 42ta-gainst. valve seat -4 Lto: thereby? maintainasubstantially; liquid tightwsealsbetween valve. seat 41 and valve.- 42W and between valve: r 42- and-lend. head..- 2.

The arrangement-is; such thatfa when :thespurnp is adjusted to deliver liquid intone. direction and cylinder barrel (31s rotated the gear. pump; liquid: acting; upon "the shoulders"?- I -l -Wi11 move each-.piston l 9 -l flsoutwardtdu-ringr one-half ofeach revo-lution. ofa. cylinder barrel 3' and each-piston- 9l 0; willrbe forced-inward. during" the other. half of a each revolution. oiqcyzli-nder barrel Sc -by means to -,.be.-presently deseribeds The-portions A 025 the? outWardmoV-ingg pistonsewillzdrawsliquid into-thev p9ItiOHS:-8v0f=- their: cylindersrthrough the pas:-

sages-x411 connected theretoevalve-port 45,-, holes;

5|, hold-up motors 52, passages-=53=-andipassage 41-from-channel 49v Portionsf-lt-tof the? inward movingpistonszwilleject liquid from thee-portions.

81 of their cylindersthrougl'rthepassages?M20011:

toi-move valve-42' away;-:fromvalve seatrd l; Howe-=- ever; the same? pressure: actsupone-ther' endsa oi:- the; cylinders Hand thepistonsb 8:of;- =therholdeup motorson :the; high pressure-side ofithe pump and; thereby enablesmthosee motors: :to urge: valve?- 4a. against -,valveseat: 4 l with aw-forcesproportional toapumpipressure-e, The ibloweefi .force alsoo-tendsw tdmove:cylinderwbarrel:3vaway fromsvalvex li ibut isprevented ifrom :doinggso --by--bearing s .5 and jfift b-yrthe pressureecreatedeby; pistons sie ta-noting UPOHTthB-TB&-l;"filld$ ooficylinderx-portionsgzs ands-by. gear pump pressure: acting?" upon zthezr reark ends: of cylinder portions 7: Thepartsare sotnroportinned-that I the.- sum- :of the domes-exerted:b-yvthe; liquid upon. the rear ends-oft cylinder portions: '1 and-8 is *nearly as;- greatea'sthe; b10WOfi=-.-fOlCe.-aSQ v that onlyasmalhaxial loadis:irnposedeupenbeare ings 5:, andiii.

The;v magnitude onthev.v bloweofir force at: any

given pressureistdetermined by theefiectiverarea;

of: the: face: of: thehvalve; Also; i power "losses-r in arballtrbeari-ng; vary: directly: inzsaccordanceawitii'. tlieesizer fiitheibearing; Thereforeeinmrderrto keep;- ther. bloweofizffo'rce and; the: bearing: losses: amminimums, ;the; effective areawof; valve; 4 2:;and5 the:sizesoieibearingfiisliould:beras 'sma'lhasxpose siblea. Thisciseaccomplished byextendingizpasesages: Alli-radially inward from; their;'respective:- cylinders;- andithen extending them: axiallyfoute WaIdTaSFCIGSBftOYthBi rotor: axis asc:isipracticable: so that the effective areazoft: thei'face oi valve: dkandfiherzdiameter of: b-earingfir5i'may be-minimum;

Sincere; pump. ordinarily? has :an odd?v number; ofiicylinders;;thes.number:oft passages 40 T contain: ingzliquid under pressure willchange from odd to: even: or from"; even: to odd eachitimei a passage? 40: passess-from: one va-lve'porti'to-ihe other. If" thEf'FhQldI-UIJ5"II101JOIS WereT-made' large enough to holdzvalve :42: against'its seat when the maximum" number ofirpassagesccontainedtliquid under pres surei. the: f01'C8"BX6I.13Edi Iby' the hold-upmotors would: be 1' in excess Y of requirementsvwhen: only? as minimum n'umber; of passages containedi'liquid' underr-pressureand thisexeess force would ime' pose;- ant-unnecessary drag'yupon cylin'der'barrel 3; and probably: would, oauseiv abrasion: of. valve seat". 41* and/orrveives face 43. If? the holdup" motors. werer-onlyrlarge" enough :to hold thervalve: toitsseat whenitheaninimuminumber;of passages; contained liquid under pressure, the valve. would? liftroff; its: seat .whenthe: maximum; number; of passages: 4&5 containedz liquid; underrr' pressures. Noti'onlmdoes the; -rmagnitude' of: the b'lowf-oifforce:

vantrbutra'lso the; center: of the? blOWi-Oii force-a shif'tstradiallyr in response to eaclt. variation: in: the numben: of? passages: 492: containing." liquid undenrpressure-s,

In: order" to: compensate for variations: in the:

1 tionakhold-upforceon valveali'ieachitime azpas= sagedllrregisters zwithwax duct fifideadingirom-the cylindenfil of that motor:

Pistons 9ll! haveztheuouter ends orheadsz there'ofjna'de spherical and in contactrzwith a flat reaction; surface: 54-- formed upon arr: annular thrust member whichwex-tendsr around shaft-4t and willfi efiectireciproeation: of; pistons 9.- -lU;when@ its: axisaisinclinedrtothecylinder: barrel axis: and cylinder? barrel: is: rotated: The; thrust;

" member: been-:xslrown :as. having a? tubular outenparti 65-; whi-chr has (its rear end flangedand reaetionysurfa-ee 6' 1 "fOI'IHEdTthBIBOH; and an: inner: tubular part Ste-Which vtelescopes with part- 55: andrhasxits front endiflangedanddnengagement.

? with a, valve like hold-up;elementzorzhvdraulie thrust bearing 76: presently to. be described.-

Thrustamember; 55-66.-is rotatablysupported: withinaezhollowl reaetionzmem-ber: or cradle- 58' having imthe irontewall thereof an: openingeSQa throughmhichshaft drextendssr Cradle Gil ie-pitifoted near its rear end upon two trunnions l and H which are fixed in opposite side walls of case I in alignment with each other and restrain cradle 68 from axial movement While permitting it to be swung thereon through limited angular distances to vary the angle between surface 64 and the axis of cylinder barrel 3. The common axis of trunnions T0 and H passes through the plane of reaction surface 64 so that swinging cradle 68 upon the trunnions causes surface 64 to rotate upon the trunnion axis.

Cradle 68 preferably is swung upward and downward upon trunnions and H to vary pump displacement and to reverse the direction of pump delivery by hydraulic means including servomotors which are energized by liquid supplied thereto from gear pump I 9-29 under the control of a suitable pilot valve but for the purpose of illustration the pump has been shown provided with manually operable means including a handwheel l2 (Fig. 8) which is threaded upon a rod 13 and is restrained from axial movement by a socket 14 carried by case I. Rod 13 extends through case I and is connected by a ring 15 to a projection 16 carried by cradle 68 near the front end thereof. When wheel 72 is rotated in one direction or the other, rod 13 will swing cradle 68 upward or downward upon trunnions l9 and H and thereby vary the angle between reaction surface 54 and the axis of cylinder barrel 3.

Thrust member 95-65 has been shown as being rotatably supported within cradle 68 by two bearings TI and 18 which have the inner races thereof fitted upon part 65 and the outer races thereof fitted in cradle 68. The inner race of bearing Tl engages the inner face of the flange on part 65, the ouer race of bearing 18 engages a shoulder 19 formed on cradle 68, and a spacer ring 80 is fitted between the inner races of the two bearings so that the two bearings and spacer ring prevent thrust member 6566 from being moved forward by the pumping forces.

When cylinder barrel 3 is rotated, thrust member 65-66 will be rotated by the frictional contact of pistons 9-49 with reaction surface 64. If surface 64 is normal to the cylinder barrel axis as shown in Fig. 1, pistons 9-4 9 will not be reciprocated in response to rotation of cylinder barrel 3 but, if cradle 68 is swung upon trunnions 10 and H to incline reaction surface 64 to the cylinder barrel axis as shown in Fig. 2, each piston will be moved progressively inward by thrust member 6556 during one-half of each revolution of cylinder barrel 3 and it will be moved progressively outward during the other half of each revolution of cylinder barrel 3 by the pressure acting upon its shoulder I l.

The outer end or head of each piston 9-l0 is made spherical so that reaction surface 64 will engage the head of each piston upon a single contact spot in all positions of thrust member 65-456. When reaction surface 64 is normal to the cylinder barrel axis the contact spot is on the axis of the piston but at that time rotation of cylinder barrel 3 does not cause reciprocation of the pistons and the outer end of each piston revolves about the cylinder barrel axis in a circular path so that there is no relative movement between it and surface 64.

When reaction surface 64 is inclined to the cylinder barrel axis, the contact spot is off-set from the piston axis, the piston is reciprocated during rotation of the cylinder barrel and its outer end or head revolves in a pathwhich is slightly elliptical so that there is a slight relative movement between the piston head and surface 64. The radius of the piston head preferably is such that the contact spot is adjacent the periphery of the piston when surface 64 has a maximum inclination to the axis of cylinder barrel 3. The portion 9 of each piston 9|0 preferably is of such a diameter that the contact spot may be offset far enough from the piston axis to cause the piston to rotate in its cylinder as it reciprocates therein to thereby eliminate sliding movement between the piston and reaction surface 64.

Since reaction surface 64 engages each piston upon a single spot, the pumping force transmitted to that piston is limited by the bearing value of that spot. The pumping force required to enable a pision to create pressure is equal to the product of the pressure and the cross-sectional piston area subjected to that pressure. If the piston were of uniform diameter and the radius of its head were such that the contact spot would be adjacent the periphery of the piston when the inclination of reaction surface 64 was maximum, the contact spot would not have sufficient bearing value to transmit the pumping force necessary to enable the piston to create a high pressure in its cylinder.

However, by increasing the radius of the piston head, the bearing value of the contact spot is multiplied by an amount approximately equal to the square of the amount by which the radius of the piston head is multiplied, but increasing the piston head radius necessitates increasing the diameter of the outer portion 9 of the piston in order that reaction surface 94 may engage the spherical piston head when the inclination of surface 64 is maximum.

Therefore, by making piston portion 9 larger than piston portion 8 and providing it with a spherical head having such a radius that the contact spot is adjacent the periphery of the piston when the inclination of surface 64 is maximum, a very high pressure can be created and the radial components of the pumping forces are landed upon a bearing surface of substantial area.

If the pistons were connected to the thrust member through universal joints so that the pistons would be retracted by the thrust member and universal joints were arranged within the cylinders according to common practice, the pump could not create high pressures for the reason that a universal joint small enough to be contained within a cylinder would not be capable of transmitting a pumping force large enough to create a high pressure in that cylinder. If the universal joints were made large enough to transmit large pumping forces and were arranged outside the cylinders, they would occupy so much space that fewer pistons and cylinders could be arranged in the cylinder barrel and the volumetric capacity of the pump would be correspondingly reduced. But by making the outer portion 9 of each piston larger in diameter than the pumping portion 8 and providing it with a spherical head which makes a spot contact with the reaction surface, the pump is capable of delivering a large volume of liquid at a high pressure.

The pumping force, which moves a piston inward when the pump is creating pressure, is transmitted through the contact spot on that piston and is normal to reaction surface 64. The umping force is opposed by the pressure in the cylinder of that piston which causes it to be resolved into an axial component, which moves the piston inward, and a radial component which ll bearings I1 and 18 are relieved of nearly all axial loads so that the bearing losses are very low.

Liquid escapes at a minute rate from groove 83 and forms between the abutting faces of element BI and thrust member 65-66 a lubricating film which prevents metal-to-metal contact. The area of this film is limited for the reason that the contact face of element 61 extends only a very short distance inward and a very short distance outward from the edges of the grooves and the distance between each end of grooves 83 and 84 and the adjacent end of a drain groove 65 is very short.

The hold-up force is transmitted to thrust member 65 and 66 through the liquid in groove 83 and the lubricating film. The liquid in groove 83 constitutes a liquid bearing which is far more efficient than a mechanical bearing as it has been found in practice that only a very small torque is required to effect relative rotation of two parts which are urged together by a very large force and have a liquid bearing of this type therebetween.

When cradle 68 is swung downward below its neutral position, the pump will function in the above described manner except that it will discharge liquid into channel 49, the opposite side of the pump will be the discharge side, and pressure will extend from channel 49 to holdup motors 9I and 93 and cause them to exert hold-up forces upon thrust member 6566 in opposition to the pumping forces exerted thereon.

By providing a hold-up element or hydraulic thrust bearing to take the greater part of the piston thrust, bearings I1 and I8 may be much smaller than would be necessary if they had to take the entire piston thrust and, consequently, the bearing losses are reduced to a minimum.

The area to which the hold-up force is applied should not extend radially outward beyond the inner race of bearings 11 and I8. Consequently, the radius of grooves 83 and 84 is considerably smaller than the radius of the circle upon which pistons 9-46 are arranged. Keeping the radius of grooves 83 and 84 small is advantageous for the reason that, while the liquid in grooves 83 and 84 constitutes a substantially frictionless bearing, rotation of thrust member 65-66 causes the lubricating film of liquid between the thrust member and the faces of the lands surrounding grooves 63 and 84 to be sheared which causes some drag upon the thrust member and, by keeping the radius of grooves 83 and 84 small and thereby keeping the area of the lubricating film small, the drag is reduced to a minimum.

Pumping forces are transmitted from thrust member 65'66 to pistons 9-I 6 through an angle of nearly 180 and, if each of grooves 83 and 84 extended through an angle of nearly 180 as does each of the ports 45 and 46 in valve 42, the center of the hold-up force exerted upon thrust member 65-66 by element 61 would be radially inward a substantial distance from the resultant of the pumping forces and a moment would be created which would tend to tilt the thrust member and thereby impose an additional load upon bearings TI and '18.

However, the center of the hold-up force may be moved radially outward into alinement with the resultant of the pumping forces by reducing the angular lengths of grooves 83 and 84 in accordance with the difference between the radius of grooves 83 and 84 and the radius of the piston circle and by providing drain grooves 85 between the adjacent ends of grooves 83 and 84. For

; example, each of grooves 83 and 84 extends through an angle of about 124 in the pump shown and the center of the hold-up force is approximately in alinement with the resultant of the pumping forces. In another pump, it was necessary to reduce each of the grooves 83 and therein and a relief valve I26 connected thereto.

Channels 49 and 56 are connected, respectively, by two channels I2I and I22 to casing H6 at two points upon opposite sides of channel H8 and channels I2I and I22 are connected, respectively, by channels I23 and I24 to the adjacent ends of casing I I6. The arrangement is such that, when the pump is reversed, it will at first tend to discharge through valve casing H6 into reservoir H5 but relief valve I20 will resist discharge of liquid therethrough and thereby cause pressure to be created. This pressure will extend from discharge channel 49 or 50 through channels I2I and I23 or channels I22 and I24 and shift valve II? to a position in which the intake side of the pump is connected to reservoir H5 and the discharge side of the pump is blocked therefrom. The pressure created by the pump is limited by one or the other of two high pressure relief valves I25 and I26 which are connected between channels I2I and I22.

The invention herein set forth is susceptibl of various modifications without departing from the scope of the invention which is hereby claimed as follows:

1. In a hydrodynamic machine, the combination of a case, a shaft journaled in said case and extending through the front end thereof, a cylinder barrel fixed upon said shaft to rotate therewith and having a plurality of cylinders arranged therein around and parallel to said shaft and a passage leading from each cylinder through the rear end of said cylinder barrel, a valve arranged upon the rear end of said cylinder barrel and cooperating with said passages to control the flow of liquid to and from said cylinders, a piston fitted in each cylinder and extending forward beyond the front end of said cylinder barrel, a thrust member cooperating with said pistons and adapted to force each piston rearward and cause it to eject liquid from its cylinder during one half of each revolution of said cylinder barrel, a reaction member arranged forward of said cylinder barrel and restrained by said case from movement axially of said shaft, a mechanical bearin carried by said reaction member to rotatably support said thrust member and to transmit pumping forces from one to the other, and means for relieving said mechanical bearing from at least a part of said pumping forces including a holdup element engaging the front endof said thrust member andv having grooves in the rear face thereof, hold-up motors reacting against said reaction member and adapted when energized to urge said element against said thrust member, and means for supplying liquid from said cylinders to said hold-up motors and said grooves.

2. In a hydrodynamic machine, the combination of a case, a shaft journaled in said case and :exteridingithroughthei front end thereofluatcylindercb arrel'zfixed"uponisaidrShaft' tovrotateitherei'withlandhavinga pluralitynfrcylinders arranged therein around. *andiparallel to said :shaft and a passage 3 leading from each cylinder through the rear end of said cylinder barrelgavalve arranged upon :the :rear rend-f i said :cylin'der :barr'el and cooperating with :Lsaid'lqaassages to ocontrolithe flow of liquid :toaand 1T from saidi'cylinders, apiston fitted in each icylin'der eandaextending forward beyondithe frontfiendrof saidcylinderibar- :rel, a thrustsrn'ember. cooperating:withisaidzpisittonsfilandead'aptedzto forcereach piston rearward and :cause it "to *sejtectf liquid fromlits Jcylinder :durin 'onejihalf of '583011? revolution :of 'saidicylinzderbarrel; a .reactionrmeinbersarrangediforward i015 irsaid cylinder 'rbarrel land restrained by flsaid -:oase' from movement:axially ofrsaid shaft, a me- -chanical bearingicarriedibyisaid reaction meniber to rotatably support: said thrust tmem'ber: an'd to itransmit pumping-iforceszfrom oneito .ithe-rother, and means formelievingi said mechanical Jbearingifrom at least' a part ofsaid :pumping iforces :including; .a hold up-=elen 1ent engaging :the front end of said =thru'st mem:ber sand having rgrooves in the-rear fa'oezthereof, hol'd 'upimotors arranged AVith-ill said element-and reactingtagainst said reaction member, and 1 means 'for supplying i liquid .Lfrom-"said cylinders tosaid hold-up motors an'd said=-grooves -to oause-said-=element to exert h'old- -up"forces upon'said thrust member in opposition to said pumping forces 1 and to provide a liquid Lbearing between said element and said thrust member.

'-3. In hydrodynamic machinepthe combination of a-ca'se,- a-lcylirider barrel rotatably supported'avith-in"said case= an d i1aving--'a plurality of cylinders arranged therein around and parallel -'to its axis of rotation -arid apassage leading from each cylinderthroughthe rear end of' said cyl-in- -der barrel, -a piston fitted 1 in *each cylinder and extending forward beyondthe front end oi -said cylinder barrel, a v'alve arranged upon' the 1 rear end ofsaidcylinder barreland cooperating with said-"passages to control the fiow-ofliquid to "and "from said cylinderspa reactionmemberfiarranged "forward-" of said "cylinderbarrel and restrained by said case from-movement axially of said cyl irfder :barrel; a thrust member-married -bvsaid reaction member an'd ha-Ving -upon the =rearerid thereof --a"reaction surfaee vvhich 'engages the outer ends ot :.:said pistons 'and --'is inclined to the cylinder barrel axis to forceeach "piston -rearward and "cause it to eject liquid "from its cylinder during one half or eachrevolution of said -cyIinder baP- rel, a-mechanical bearing'carried bysaid reaction member 'to rotatably-support saidthrust member "and to transmit pumping forces 'from'one to the other, and means" for relieving sam -mechanical hearing from at least -a "part -i'of said pumpi-ng L'forces' including-a"hold up element engagingthe "front end -"of said thrust member a=ndhaving 1 grooves 'in the rear face 'thereof, hold-upmotors reacting "against 'said *reaction :member and "adapted when"energi-zed to urge said element against-said thrushmerhber; andmeans for supplying' liquid from-saidcylinders to said hold up 1 motors and-said grooves.

4. In a -hydrodyna'micmachina the combination of a case, a cylinder barrel rotatably supported =Within said' case and having a plurality 1 of 'cylinders arranged therein around and paral-'- lel to its axis of rotation and a-passage' leading "fromeach cylinder through -the rear endof said "cylinder 5 -b arrel; a-piston' fitted in "each cylinder -andrextendingrforward beyond 1" the :frontiend of said cylinderbarrel, azvaive: arranged ;.upon v: the trean end :of said: cylinder :barrel and cooperating with said z passages -to control the. flow of liquid to and ffrom-isaidcylinders, a reaction member arranged forward of said1cylinder barreland're- -strained by-;said case "from movement axially'of :said nylindervbarrel; a thrustlmembericarried by said reactionmemberandmaving uponthe :rear endfithereof ameactiomsurface which engages the outer ends of -said 1 pistons "and is inclined :to :the cylinder-Jbarrel :ax'is to force each ipiston :rearmard and cause itrtorej ectl'liquid'from itsicylinder durirrg one iialf ofl each revolution of said cylintler barrel, mechanical bearing carried byJSaid reaction member to rotatably support saidathrust member: and l to transmit pumping forces from one to the :other, :and means for relieving said mecharii'cal bearing from atleast a partuof said .pun'n'ning forcesincluding :a hold-up element enga'ging 'theWrontend. of: said thrust .member and havin-gsgrooves 'in the rear "face thereof ,Jhold-up 'm'otors =arranged within said element and reactingagainstisaid'reaction noember; and means for "supplying liquidfrom said cylinders: to said holdup motors' and said grooves to cause saidielement :to exerthold-up forces upon said thrustm'emher in QppQSi tiQnto'said :pumping forces and to "provide a -liquid bearing between said 'element and said thrust member.

'5. In a hydrodynamicunachinegthe combina- I tion- 'o'f =a ca'se; acylinder 'barrel 1 rotatably sup- "portedwithin said case and'havingra plurality "of cylindersarranged therein around and paral- ---1e1-' to its--axis of rotationand 'a passage leading Efremeach oylinder through the rear end of "said "cylinderbarr'el a@valve arranged upon therear e'nd'of said cylinder barrel and cooperating with said passages to: control the' flow of liquid to and fromsaidcylinders, each'of said cylinders in- -luding an inner -pumpingportion and an outer .Jgui'd-ing portion larger in diameter "than said pumping-portion, pistons'fitted in said cylinders, eacho'f said pistons' including a pumping pertiQn 'fitte'd in' the pumping portion of-its cylinder and at larger-= guidingiportion' fitted in' the guiding portion cif its cylin'der, ':a reaction "member arranged forwardof said cylinder barrel and-"restra-i-ned by ea-id case"from*movem'ent axially of *sai'd cylinder barrel, a thrust member :carried bysa-id reaction member and having upon 1 the rear en'd thereof a reaction surface which engages 'the' outer ends of said pistons and is in- 'clin'e'd to 'the cylinderbarrel-axis to force each "piston'rearwar'd and cause it to eject liquid from its *cylinder during one half I of "each revolution of'said' cylinder barrel, means for maintaining in the inner part 'of' the- 'gui'ding portion of each zof said *cylin'ders :a liquid pressurewvhich urges said pistons against said reaction surface and moves said pistons outward during the other half f each-revolution of-said cylinder barrel, a mechanical bearing carried by said reaction member =to -rotatablysupport-said thrust member and (35 to tranSm'it' pumpirIg forces 'from one to the "other, and means -'-for 'relieving"said mechanical bearing fromfat l'ea'st a part 1 of said :pumping forces including a' hold-up elementengaging the 'front 'en'd :or said thrust member and having :grooves. in the reariface thereof, hold-up motors reacting :against :said reaction member and :adapted when energized-11:0 :urge said element -against1said thrust membenuand means 'forsup- :p'lying liquid from said cylinders' to said hold-u i -motors andsaid grooves. I

6. In a hydrodynamic machine, the combination of a case, a cylinder barrel rotatably supported within said case and having a plurality of cylinders arranged therein around and par allel to its axis of rotation and a passage leading from each cylinder through the rear end of said cylinder barrel, a valve arranged upon the rear end of said cylinder barrel and cooperating with said passages to control the flow of liquid to and from said cylinders, each of said cylinders including an inner pumping portion and an outer guiding portion larger in diameter than said pumping portion, pistons fitted in said cylinders, each of said pistons including a pumping portion fitted in the pumping portion of its cylinder and a larger guiding portion fitted in the guiding portion of its cylinder, a reaction member arranged forward of said cylinder barrel and restrained by said case from movement axially of said cylinder barrel, a thrust member carried by said reaction member and having upon the rear end thereof a reaction surface which engages the outer ends of said pistons and is inclined to the cylinder barrel axis to force each piston rearward and cause it to eject liquid from its cylinder during one half of each revolution of said cylinder barrel, means for maintaining in the inner part of the guiding portion of each of said cylinders a liquid pressure which urges said pistons against said reaction surface and moves said pistons outward during the other half of each revolution of said cylinder barrel, a mechanical bearing carried by said reaction member to rotatably support said thrust member and to transmit pumping forces from one to the other, and means for relieving said mechanical bearing from at least a part of said pumping forces including a hold-up element engaging the front end of said thrust member and having grooves in the rear face thereof, hold-up motors arranged within said element and reacting against said reaction member, and means for supplying liquid from said cylinders to said hold-up motors and said grooves to cause said element to exert hold-up forces upon said thrust member in opposition to said pumping forces and to provide a liquid bearing between said element and said thrust member.

7. In a hydrodynamic machine, the combination of a case, a cylinder barrel rotatably supported within said case and having a plurality of cylinders arranged therein around and parallel to its axis of rotation and a passage leading from each cylinder through the rear end of said cylinder barrel, a piston fitted in each cylinder and extending forward beyond the end of said cylinder barrel, a valve cooperating with said passages to control the flow of liquid to and from said cylinders, two trunnions carried by said case upon opposite sides thereof in axial alinement with each other, a reaction member arranged forward of said cylinder barrel and pivoted upon said trunnions, a thrust member carried by said reaction member and cooperating with said pistons to force each piston rearward and cause it to eject liquid from its cylinder during one-half of each revolution of said cylinder barrel, a mechanical bearing carried by said reaction member to rotatably support said thrust member and to transmit pumping forces from one to the other, and means for relieving said mechanical bearing from at least a part of said pumping forces including a hydraulic hold-up element carried by saidreaction member in engagement with said thrust mem- 16 her and energized by liquid supplied thereto from said cylinders'to cause said element to exert hold-up forces upon said thrust member in opposition to said pumping forces and to provide a liquid bearing between said element and said thrust member.

8. In a hydrodynamic machine, the combination of a case, a cylinder barrel rotatably supported within said case and having a plurality of cylinders arranged therein around and parallel to its axis of rotation and a passage leading from each cylinder through the rear end of said cylinder barrel, a piston fitted in each cylinder and extending forward beyond the end of said cylinder barrel, a valve cooperating with said passages to control the flow of liquid to and from said cylinders, two trunnions carried by said case upon opposite sides thereof in axial alinement with each other, a reaction member arranged forward of said cylinder barrel and pivoted upon said trunnions, a thrust member carried by said reaction member and cooperating with said pistons to force each piston rearward and cause it to eject liquid from its cylinder during one half of each revolution of said cylinder barrel, a mechanical bearing carried by said reaction member to rotatably support said thrust member and to transmit pumping forces from one to the other, and means for relieving said mechanical bearing from at least a part of said pumping forces including a hold-up element engaging the front end of said thrust member and having grooves in the rear face thereof, hold-up motors reacting against said reaction member and adapted when energized to urge said element against'said thrust member, and means for supplying liquid from said cylinders to said hold-up motors and said grooves.

9. In a hydrodynamic machine, the combination of a case, a cylinder barrel rotatably supported within said case and having a plurality of cylinders arranged therein around and parallel to its axis of rotation and a passage leading from each cylinder through the rear end of said cylinder barrel, a piston fitted in each cylinder and extending forward beyond the end of said cylinder barrel, a valve cooperating with said passages to control the flow of liquid to and from said cylinders, two trunnions carried by said case upon opposite sides thereof in axial alinement with each other, a reaction member arranged forward of said cylinder barrel and pivoted upon said trunnions, a thrust member carried by said reaction member and cooperating with said pistons to force each piston rearward and cause it to eject liquid from its cylinder during one half of each revolution of said cylinder barrel, a mechanical bearing carried by said reaction member to rotatably support said thrust member and to transmit pumping forces from one to the other, and means for relieving said mechanical bearing from at least a part of said pumping forces including a hold-up element engaging the front end of said thrust member and having grooves in the rear face thereof, hold-up motors arranged within said element and reacting against said reaction member, and means for supplying liquid from said cylinders to said hold-up motors and said grooves to cause said element to exert hold-up forces upon said thrust member in opposition to said pumping forces and to provide a liquid bearing between said element and said thrust member.

' 10. In a hydrodynamic machine, the combination of a case, a cylinder barrel rotatably sup-i a manac ported 'within said :case and having a plurality =of cylinders arranged therein around :and parallel to :its axis of rotationand a'passa'ge leading from each cylinder through the rear end-of said cylinder barrel, a valve cooperating withsaid passages :to .control-theflow of liquid to and'from said cylinders, each ofsaid cylinders including an inner pumping portion and an outer guiding portion larger in diameter than said i-pumping portion, pistons fitted in said cylinders, each of said pistons including 'a pumping portion :fitted in the pumping portion of its cylinder and 'a larger guiding portion fitted in the guiding portion *of its cylinder, two trunnions :carried "by said case upon opposite sides thereof in "axial :alinement with each other, a reaction :member arranged forward of said cylinder barrel andipivoted *upcn said trunnions, a thrust member carried "by said reaction member and cooperating with said pistons to force each piston rearward "and cause it to eject liquid from its cylinder during one half of each revolution of said cylinder barrel, a memechanical bearing carried by said reaction member to 'rotatably support said thrust'memher and to transmit pumping forces from one to the other, and means for relieving said mechanical bearing from at least a part of said pumping forces including a hydraulic hold-up element carried by said reaction member in engagement with said thrust member and energized by liquid supplied thereto from said cylinders to cause said element to exert hold-up -forces upon said thrust member in opposition to said pumping forces "and to provide a liquid bearing between said "element and said thrust member.

11. In a hydrodynamic machine, the combination of a case, a cylinder barrel rotatably supported within said case and having a plurality of cylinders arranged therein around and parallel to its axis of rotation and a passage leading from each cylinder through the rear end of said cylinder barrel, a valve cooperating with said passages to control the flow of liquid to and from said cylinders, each of said cylinders including an inner pumping portion and an outer guiding portion larger in diameter than said pumping portion, pistons fitted in said cylinders, each of said pistons including a pumping portion fitted in the pumping portion of its cylinder and a larger guiding portion fitted the guiding portion of its cylinder, two trunnionscarried by said case upon opposite sides thereof in axial alinemen-t with each other, a reaction member arranged forward of said cylinder barrel and pivoted upon said trunnions, a thrust member carried by said reaction member and cooperating with said pistons to force each piston rearward and cause it to eject liquid from its cylinder during one half of each revolution of said cylinder barrel, a mechanical bearing'carried by said reaction member to rotatably support said thrust member and to transmit pumping forces from one to the other, and means for relieving said mechanical bearing from at least a part of said pumping for'ces'including a hold-up element engaging the front end of said thrust member and having grooves in the rear face thereof, hold-up motors reacting against said reaction member and adapted when energized to urge said element against said thrust member, and, means for sup-' plying liquid fromsaid cylinders to said hold-up I motors and saidgrooves. I 7 12; In a hydrodynamic machine, the combination of a case, acylinder barrel rotatably sup-' ported within said case and having a plura'lity 118 of cylinders arranged therein "around and parallel to its axis of rotation and a passage leading from'each cylinder through the rear end of said cylinder barreLa valve cooperating with said passages to'c'ontrol the flow of liquid to and from said cylinders, each of said cylinders including an -inner pumping portion and an outer guiding portion larger in diameter than said pumping portion, pistons fitted in saidcylinders, each of said pistons including -a pumping portion fitted in the pumping portion-of its cylinder-and 'a larger guiding portion fitted in the guiding portion of its cylinder, two trunnions carried "by said ca'seupon opposite sides thereof in axial alinement with each other, a reaction member arranged forward of said cylinder barrel and pivoted upon said trunnions, a thrust member carried by said reaction member and cooperating with said ,pis tons to force each piston rearward and cause it to eject liquid from its cylinder during one half of each revolution of said cylinder barrel, a mechanical bearing carried by said reaction member to rotatably support said thrust member and to transmit pumping forces from 'one to the other, and means for relieving said mechanical bearing from at least a part of said pumping forces including a hold-up element engaging the front end of said thrust-member and having grooves the rear face thereof. holdup motors arranged Within said element and reacting against said reaction member, and means for supplying liquid from said cylinders to said hold -up motors and said grooves to cause said element to exert hold-up forces upon said thrust member in opposition to said pumping forces and to provide a liquid bearing between said ele= ment and said thrust member. I

1-3. In et -hydrodynamic machine, the combination of a case, a cylinder barrel rotatably supported within said case and having a plurality of cylinders arranged therein around and parallel to its axis of rotation and a passage leading from each cylinder through the rear end of said cylinder barrel, a piston fitted in each cylinder and extending forward beyond the end of said cyl'- ind-erbarrel, a. valve cooperating with said passages to control the flow of liquid to and from said: cylinders, two trunniohs carried by said case upon opposite sides thereof in axial alinement with each other, a reaction member arranged forward of said cylinder barrel and pivoted upon said trun nions, a thrust member carriedby said reaction member and cooperating with said pistons to force each piston rearward and cause it to eject liquidfrom its cylinder during one half of each 'revolu tion of said cylinder barrel, a mechanical bearing carried by said reaction member to rota-tablysupport said thrust member and to transmitpumping forces from one to the other, and means for relieving said mechanical bearing from at least a part of said pumping forcesincluding hydraulic hold-up means arranged upon opposite sides of the centerlineof said machine and engaging the front end of said thrust member, and means for directing liquid from the c linders from'which liquid is ejected to thehold-up means on only the same side of said centerline as those cylinders;

14. In a hydrodynamic machine, the combination of a rotor having a plurality of pistons and cylinders arranged therein parallel to the axis of rotation thereof, a reaction member arranged at one end of said rotor for engaging the outer ends of said pistons and rotatable upon an axis} which is normally incl-inedto the axis 'of' sai'd' rotor to thereby effect reciprocation of said pistons during rotation of said rotor, a substantially fiat valve seat arranged upon the other end of said rotor, a cylinder port extending from each cylinder through said valve seat, a floating valve having a substantially flat'face to engage said valve seat and ports to cooperate with said cylinder ports to thereby control the flow of liquid to and from said cylinders, and hold-up motors responsive to pressures in said cylinders for urging said valve against said seat, said valve being entirely unsupported by said hold-up motors and being free to tilt a limited distance in any direction relative to the axis of said rotor to thereby enable said hold-up motors to hold the face of said valve uniformly in contact with said valve seat re ardless of slight misalinement or deflections of parts of said machine.

15. In a hydrodynamic machine, the combination of a drive shaft and a cylinder barrel rigidly secured to each other to form a substantially unitary rotor having a substantially flat valve seat upon one end thereof, a bearing arranged around said shaft to support said rotor at one end thereof, a second bearing arranged around said valve seat to support said rotor at the other end thereof, pistons and cylinders arranged in said cylinder barrel around said shaft parallel to the axis thereof, a reaction member arranged at the end of said cylinder barrel opposite said valve seat for engaging the outer ends of said pistons and rotatable'upon an axis which is normally inclined to the axis of said rotor to thereby effect reciprocation of said pistons during rotation of said rotor. a cylinder port extending fromeach' cylinder through said valve seat, a floating valve having a substantially flat face to engage said valve seat and ports'to cooperate with said cylinder ports to thereby control the flow of liquid to and from said cylinders, and hold-up motors responsive to pressures in said cylinders for urging said valve against said seat, said valve being entirely unsupported by said hold-up motors and being free to tilt a limited distance in any direction relati e to the axis of said rotor to thereby enable said hold-up motors to hold the face of said valve uniformly in contact with said valve seat re ardless of slight misalinement or deflections of parts of said machine.

16. In a hvdrodynamic machine, the combination of a rotor having a pluralit of pistons and cylinders arran ed therein parallel to the axis of rotation thereof, a reaction member arranged at one end of said rotor and having a substantially fiat face normally inclined to the axis of said rotor and engaging the outer ends of said pistons to effect reci rocation of said pistons during rotation of said rotor, a support for rotatably supporting said reaction member withits axis of rotation intersecting the axis of said rotor in the plane of said face, means for piv-1 otally supporting said support upon an axis; which extends through the pointat which the axes of said rotor and said member pass through the plane of said face, means for tilting said support upon said supporting means to thereby;

vary the inclination of said reaction member relative to the axis of said rotor, a substantially flat valve seat arranged upon the other end of said rotor, a cylinder port extending from each cylinder through said valve seat, a floating valve having a substantially flat face to engage saidvalve seat and ports to cooperate with said cylinder ports to thereby control the flow of liquid to and from said cylinders, andholdeup motors responsive to pressures in said cylinders fo'r urg+ ing said valve against said seat, said valve being entirely unsupported by said hold-up motors and being free to tilt a limited distance in any direction relative to the axis of said rotor' to thereby enable saidhold-up motors to hold the face of said valve uniformly in contact with said valve seat regardless of slight misalinement or deflections of parts of said machine.

17. In a hydrodynamic machine, the combination of a drive shaft'and a cylinder barrel rigid 1y secured to each other to form a substantially unitary rotor having a substantially flat valve seat upon one end thereof, a bearing arranged around said shaft'to support said rotor at one end thereof, a second bearing arranged around said valve seat to support said rotor at the other end thereof, pistons and cylinders a'rranged'in said cylinder barrel around said shaft parallel'to the axis thereof, a reaction member arranged at the end of said rotor opposite said valve'seat and having a substantially fiat face normally inclined to the axis of said rotor and engaging the outer ends of said pistons to effect reciprocation of said pistons during rotation of said rotor, a support for rotatably supporting said reaction member with its axis of rotation intersecting the axis of'said rotor in the plane of said face, means for pivotally supporting'said support upon an axis 'which extends through the point at which the axes of said rotor and said member pass through the plane of said face, means for tilting said support upon said supporting means to thereby vary the inclination of said reaction member relative to the axis of said rotor, a cylinder port extending from each cylinder through said valve seat, a floating valve having a substantially flat face to engage said valve seat and ports to cooperate with said cylinderports to thereby control the flow'of liquid to and from said cylinders, and hold up motors responsive to pressures in said cylinders for urging said valve against said seat, said valve being entirely unsupported by said hold-up motors and being free to tilt a limited distance in any direction relative to the axis of said rotor to thereby enable said hold-up motors to hold the face of said valve uniformly in contact with said valve seat regardless .of slight misalinement ordeflections of parts of said machine. 7 r

18. In a hydrodynamic machine, the combination of a rotor having 'a plurality of pistons and cylinders arranged therein parallel to the axis of rotation thereof, a reaction member arranged at one end of said rotor and having a substantially flat face normally inclined to the axis of said rotor and engaging the outer ends of said pistons to effect reciprocation of said pistons during rotation of said rotor, a'support for rotatably supporting said reaction member with its axis of rotation intersecting the axis of said rotor in the plane of said face, means for pivotally supporting said support-including trunnions arranged upon opposite sides thereof engage said valve seat, and ports tocoop-erate:

hold-up motors responsive'to; pressures in, saidcylinders. for urging said valve againstsaid seat; aid valve being entirely uns pported by said hold-up motors. and bein free to; tilt. limited distance in any direction: relative to: the. axis or said rot r to thereby enable said.- hold up-nrotors to hol the face of saidivalvev uniformly in con:-

ta t with said valve seat re ardl s; of; sli htimisw alinement or defl ctions Qt Parts of" Said mac chin 19, In; a hydrodynamic: maehine, the combine: ion of a driveshaft and a. cylind r bar e ri idly secured to a h other to, form a. substantially.

unitaryrotor having: a. substantially fiat. valve 22 face,- so that each piston is forced into its cylinder by said-surface during one halfof each revolution of said'rotor, the outer end or head of each piston being so: shaped; that it engages said surface at onev side only of the piston. axis and causes the pumping. force transmitted from said surface to said piston to be resolved into an axial component which moves the. pistoninwardand a radial comseat.v upon. one end there f; a. earin arr nged. around said shaft to support. said rotor at one.

end thereof, a. second; beeringarranged around. saidvalve seat to supportsaidrotor-at the other end thereof,; pistons and. cylinders: arran ed in said cyl nder barrel, around said; shaft. parallel" ta-theaxis. thereof, a, reactitmv member arranged at: the. end of said rotor opposite, said valve seat- A and having. a. substantially flat; face'normally in..- clined to the axis of: said: rotor and-.engaaingthc. out r ends. of said pistons; to,- effect. reciprocation of Said pistons during rotation of said rotor, a

support for rotatably supporting said. reaction member with its. axis of rotation intersecting;

the. axis ofv said rotor in the plane of. said face, m ans for pivotally supporting said support including trunnions arranged upon opposite sides thereof with the trunnion axes extending through the point at, which the axes ofsaid rotor and said member pass through the plane; of saidface, means for tilting. said support upon. said trunnions to thereby vary the inclination of said reaction member'relative to the axis of said rotor,

a cylinderport extending from' each cylinder through said.- valve seat, a floating valve having a. substantially flat. face to engage said valve seat and ports to cooperate with saidcylinder ports to. thereby control the flow of liquid to and from said cylinders, and hold upl motors respontion relative to the axis of said rotor to thereby' enable said hold-up motors to hold the face of said valve uniformly in contact with said valve seat regardless of slight misalinement or deflections of parts of said machine.

20. In a pump, the combination of a rotor having a plurality of cylinders arranged therein parallel to the axis of rotation thereof and a substantially fiat valve seat on one end thereof,'a floating valve engaging said seat to control the flow of liquid to and from said cylinders, holdup motors responsive to pressure in said cylinders for urging said valve against said seatg said valve being entirely unsupported by said hold-up motors and being free to tilt a limited distance in any direction relative to the axis of said rotor to thereby enable said hold-up motors to hold the face of said valve uniformly in contact with said valve seat regardless of slight misalinement or deflections of parts. of said machine, a substantially fiat reaction surface arranged atthe other end of said rotor and rotatable upon an axis which is normally inclined-to the axis-,of rotation or said rotor, and a cylindrical piston fitted in each of said cylinders and having an'int'egral outer end or head in engagement with said surponent which is'transmitted through the piston to thewall of-its cylinder and so that the axis of the piston remains substantially in alinement With the same pointon said surface during rota.-. tion of said. rotor and said surface at the samespeed.

21. In; a hydrodynamic machine, the combination of a, rotor having a shaft extending from. only one end thereof and a substantially flat valve seat on the other endthereof; a bearing arranged around said shaft to support said rotor'at one end thereof, a second bearing arranged around said valve seat to: support said rotor at the other: end thereof; pistons and cylinders arranged in said cylinder barrel around said shaft parallel to the axis: thereof; areaction member.- arranged at the end of said cylinder barrel opposite said valve seat for engaging the outer. ends of said pistons and rotatable upon an axis which is normally in-- clined to the axis of said rotor to thereby effect reciprocation of said pistons during rotation of i said. rotor; said rotor having a passage extending from eachof said cylinders radially inward and? axially outward through said valve seat and. constituting a. cylinder port, a floating valve having a substantially flat face to engage saidvalve seat and ports to cooperate with said cylinder ports; to thereby control the flow of liquidto and from said cylinders, said cylinder ports and said valve ports being arranged as close as practicalto the axis of said rotor to thereby reduce to a the valve area in contact with said valve. seat, and" hold-up motors responsive topressures in said cylinders for urging said valve against said seat.

22; In a hydrodynamic machine, the combination of a rotor having a'shaft extending from only one. end thereof and a substantially flat valve seat on the other end thereof, a bearing; arranged around said shaft to support said rotor at one end thereof, a second bearing arranged around said valve seat to support said rotor at the other end thereof, pistons and cylinders arranged in said cylinder barrel around said shaft parallel to the axis thereof, a reaction member arranged at the end of said cylinder barrel opposite said valve seat for engaging the outer ends of said pistons and rotatable upon an axis which is normally inclined to the axis of said rotor to thereby effect reciprocation of said pistons during rotation of said rotor, said rotor having a passage extending from each of said cylinders radially inward and axially outward through said valve seat and con- .stituting a cylinder port, a floating valve havtical to the axis of said rotor to thereby reduce to a minimum the valve area in contact with said valve seat, hold-up motors responsive to pressures in said cylinders for urging said valve against said seat, and means independent of said hold-up motors for restraining said valve from radial movement while permitting it to have limited axial and tilting movements.

23. In a hydrodynamic machine, the combination of a rotor having a plurality of pistons and cylinders arranged therein around and parallel to the axis of rotation thereof, a reaction member arranged at one end of said rotor to engage the outer ends of said pistons and rotatable upon an axis which normally is inclined to the axis of said rotor to thereby efiect reciprocation of said pistons during rotation of said rtor, a substantially fiat valve seat arranged upon the other end of said rotor, a bearing arranged upon a portion of said rotor adjacent to said seat to support said rotor at one end thereof, said portion of said rotor being considerably smaller in diameter than the remainder of said rotor to permit said bearing to be relatively small and thereby keep the bearing losses at a minimum,

said rotor having a passage extending from each of said cylinders radially inward and then axially outward through said valve seat and constituting a cylinder port, a floating fiat valve having a substantially flat face to engage said valve seat and ports to cooperate with said cylinder ports to thereby control the flow of liquid to and from said cylinders, said cylinder ports and valve ports being arranged as close as practical to the axis of said rotor to thereby reduce to a minimum the valve area in contact with said seat, and hold-up motors connected in series with said ports and responsive to the pressures therein for urging said valve against said valve seat.

24. In a hydrodynamic machine having a rotor provided with a plurality of pistons and cylinders which are parallel to the axis of said rotor and are arranged in a circle concentric with said axis, and a thrust member arranged at the front end of said rotor and adapted during rotation of said rotor to force rearward the pistons on one side of the centerline of said machine, the combination of a reaction member arranged forward of said thrust member and restrained from axial movement, a mechanical bearing for rotatably supporting said thrust member and for transmitting pumping forces from one to the other of said members, and

means for relieving said mechanical bearing from at least a part of said pumping forces in cluding a hold-up element engaging the front end of said thrust member and having in the rear face thereof two arcuate pressure ports arranged upon opposite sides of the centerline of said machine and drain grooves arranged between the adjacent ends of said pressure grooves, hold-up motors arranged upon opposite sides of the centerline of said machine and adapted when energized to react against said reaction member and to urge said element against said thrust member, and means for supplying liquid from the cylinders on each side of the centerline of said machine to the hold-up motors and the pressure groove on the same side of said cen terline to enable said hold-up element to exert a hold-up force upon said thrust member in opposition to said pumping forces.

25. A combination as set forth in claim 24 in which the radius of said pressure grooves is less than the radius of said piston circle and each of said pressure grooves extends through such an angular distance that the center of said holdup force is approximately in alinement with the resultant of said pumping forces.

26. A combination as set forth in claim 24 in which the liquid supplied to the hold-up motors and to the pressure groove on each side of said machine is supplied thereto through only one of the motors on each side of said machine.

ADOLF GRAD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,274,391 Davis Aug. 6, 1918 2,155,455 Thoma Apr. 25, 1939 2,250,512 Vickers July 29, 1941 2,345,446 Baker Mar. 28, 1944 2,455,330 Denison Nov. 30, 1948 I V FOREIGN PATENTS Number Country a Date 527,359 Great Britain 1940 

